Latch mechanism



Patented Mar. 20, 1945 LATCH MECHANISM Roswell C. Van Sickle, Wilkinsburg, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application June 30, 1943, Serial No. 492,911

12 Claims. (Cl. 745-42) This invention relates to circuit breakers and more particularly to latch mechanism for circuit breakers.

One object of the invention is to provide an improved latching mechanism for a circuit breaker that is simple, reliable in operation and inexpensive to manufacture.

Another object oi the invention is to provide an improved high-speed latching mechanism for a circuit breaker.

Another object of the invention is to provide a circuit breaker with an improved iloating latch which is capable o1' high-speed latching and unlatching operation.

Another object of the invention is to provide acircuit breaker with an improved high-speed latching mechanism wherein the latch is mounted on movable pivots and engages directly with the breaker operating rod.

Another object of the invention is to provide a. circuit breaker with an improved latching mech- :mism wherein the latch member travels with the breaker rod a predetermined distance in both latching and unlatching operations to permit high-speed latching and unlatching.

'I'he novel features that are considered characteristic of the invention are set forth in the appended claims. The invention itself, however, both as to structure and operation, together with additional objects and advantages thereof will be best understood from the following detailed de- |scription thereof when read in connection with the accompanying drawing, in which:

Figure l is an elevational view, partly in section, of a circuit breaker operating mechanism embodying the principles of the invention; and

Fig. 2 is a fragmentary elevational view, partly inl section, showing the latch mechanism in the unlatched position.

Referring to the drawing, the circuit breaker 3, which is illustrated diagrammatically, may be of any conventional construction either of the oilbreak, air-break or gas-blast type and is adapted to be operated to the open position by means of an accelerating spring '5. The circuit breaker is adapted to be operated to the closed position by means of an operating mechanism which in the embodiment shown is of the compressed-air or gas-operated type. The operating mechanism in the embodiment shown includes a main casting II which is formed to provide an operating cylinder I3 closed at the lower end by an integral part of the casting. The upper end of the cylinder I3 is closed by means of a member I5 suitably secured thereto. Mounted in the cylinder I3 is an operating piston I1 secured to a piston rod I9 which is slidable through an air-tight opening in the top wall I5 of the cylinder. The upper end oi the piston rod I 9 is threadedly connected as at 2I to the connecting portion of a bifurcated member 23, the two arms 25 of which extend upwardly in parallel relationship. The upper ends ofthe arms 25 are operatively connected to the circuit breaker 3 through a suitable linkage.

In order to hold the breaker closed, the mem ber 23, piston rod I 9 and the piston I1 are held in closed position by means of a high-speed latch 21 supported between a pair of spaced parallel frames 29 (only one being shown) integral with and extending upwardly from the cylinder head I5. As shown in Fig. l, the left-hand ends of the frames 29 are rigidly connected by an integral cross member 3|. The latch 21 is supported by an upper link 33 and a, lower link 35, the upper link 33 being pivotally supported on a pin 31 and the lower link on a pin 39. The pins 31 and 39 are mounted in the frame member 29. The links 33 and 35 each comprise spaced parallel links (only one of each being shown) and are respectively pivotally connected to the latch 21 by pins 4| and 43. The latch member v21 is provided with an integral tail 45, the outer end of which is slotted to receive the upper end of a toggle link 41. The toggle link 41 is pivotally connected by means of a pivot pin 49 to the tail 45 of the latch member. 'I'he lower end of the toggle link 41 is pivotally connected by means of a knee pivot pin 5I to a toggle link 53, the upper end of which is slotted to receive the link 41. The toggle link 53 is pivotally mounted on a xed pivot pin 55 supported in a pair of spaced lugs 51 (only one being shown) suitably secured to the cylinder head I5. The toggle comprising the links 41 and 53 comprises a tripping toggle and is biased to a slightly overset position by means of a spring 59 coiled about the pivot pin 55 and having one end bearing against the end of the cylinder member I5. The other end' of the spring 59 is hooked over a tail '6I integral with the link '53 andprojecting inwardly therefrom substantially parallel to the top -of the cylinder. The overset position of the tripping toggle 41-53 is adjustably limited by the end of the tail 6I resting on an adjusting screw c53 threadedly engaging the member I5 and locked in its adjusted position by a lock nut 65.

In its overset position, the toggle 41--53 holds a latching projection 61 on the latch member 21 in latching engagement with a latch roller 69 disposed between the arms 25 of the member 23 and rotatably mounted on a pin 1I supported in the arms 25. The latch member 21 is biased to its latching position by means of a coil spring 13 compressed between male and female spring guides 15 and 11. The spring guide 15 is headed to retain the spring 13 and is pivotally supported on a iixed pivot pin 19 mounted in the frames 29. The female spring guide 11 is generally tubular in shape to slidingly receive the male spring guide 15 andV is yprovided with an annular flange 8| against which one end of the spring 13 bears. The spring guide 11 is also provided with a pair of spaced ears 83 (only one being shown) kin which is securely mounted a, pin 85 pressed by means of the spring 13 into a notch 81 Vin the apex of the latch member21jthus biasing theV latch member to latching position.

The manner of mounting the latch member 21 on the links 33 and 35 and the location Aof the several pivot points 31,y 39, 4| and 43 provides `a movable center C about which the latch member 21 pivots during` its latching `and unlatching movements. This center C is lccated'at theintersection of a lineA drawn through the centers 4or kthe pins 31vand 4|, and a line .Bdrawn through the centers of thepinslBii and. 43. "Referring to Fig. l, lit will be Yseen that the movable center C of the latch member 21v is located close tofthe latching vpoint :of contactfof .thei latch member with the latch roller `|59 so that the force applied by the accelerating spring V5 'through the roller -r t9 is applied to the latch member byf ashort lever arm whichJtends to rotate the'latch ,member clockwise about the movable vcenter C at"v the intersection of the center lines A andB. l'Dueto the arrangement of parts, the `iorce 'tending to move the latch member .in tunlatching direction applies a comparatively light load to the tripping toggle :l1-53 whichin its;` slightly overset position restrains the latch memberinlatching:posithe trip plunger 9|, the trip device comprises'a magnet core 93 of magnetic material, anenergizing coil 95 mounted'onl one leg of the core93,and a movable armature 91. IThe trip-plunger 9| is secured to the center portion :of the armature 91 :and extends upwardlythrough a guideopening in the center portion of the core 93 andthrough an opening in the cylinder topll.' s

*The trip `device: Bllymaybe energized in any well known manner .to eiect tripping of the breaker. When theitripidevice is energizedgthe armature 91 is moved upwardly againstthe .core

193causing upward movement ofthe .trip plunger V9|.

The upward movement' of the trip plunger acts'cn the tail 6| to rotatethe link'53 moving the knee "5| .of the tripping toggle'4|.'s3 over- ;center to the right ofthe center .line dil- 55, r

whereupon the accelerating 'spring :5, acting throughthe connecting train andthe latch roller 69. moves the latch mechanism tothe rightcausing complete collapse of the trippingtoggle. 'The latch mechanism is shown in .'Fig. k3 in its unlatched position with the v'nose ofthe latch pro- '.lectionfl resting against the ,isidecf the piston V4rod i9, being biased to vthis :position-,by the spring, 519. I

During the early part of Vthe-.unlatchingmove- .of pins 31 and t3. Thereafter, continued upward movement of the latch roller 69 continues the counterclockwise movement of the link 33 but the llink 35 reverses its direction of movement and rotates in a clockwise direction back approximately to its original position. The movement of the latch member continues toward the right and in a clockwise direction until the roller 59 moves above the latch projection 61 and the piston rod i9 engages the nose of the latch and holds the latch mechanism in the position shown in Fig. 2. During the early part of the unlatching action,

the latch surface of the latch projection 51 travels with the upwardly moving rollerfe pivoting about thepoint C. vlit will thus beV seen -that thereis no frictional load imposed on the point of contact -of the latch with the latch roller 69. Since the latch surface 'moves fwithrthe latch -rollerv 69 for at least a portion wof theunlatching movement, la greater length of time maybe usedin withdrawing the ,latch to lunlatching position. The load Aon theflatchl is released the instantthe tripping .small moment arm. `This biasing :force of the spring 13 is overcomeby .the force ofthe spring 59 which acts through the' toggle links 53 and -41 to press the nose of the' latching projection $1 against the side ofthe rod 19.

The breakerfis adapted to be closed, following an opening zoperation, by compressed gas ad- 'mitted to the cylinder I3 above the piston |1.

Compressed gas is admittedfrom an auxiliary reservoir or tank 39 to the upper-end of the cylinder |3'throughan inletpassagell controlled bya 4main linlet valve'indicated generally at |93 'securedto the `sideofithe casting Il. The openingvoperation of the main inlet valve |03 is, in turn, controlled byan electromagnetically operated 'pilot valvelt. v'I'he valve mechanism is fully disclosed in .copending application Serial No.410,686, vledseptember 13, 1941, of 'J.M. Cummingand R; C. Cunningham and assigned to the assigneeof the present invention. For this reason, a detailed disclosurepf this mechanism is not included herein since reference may be had to the above-noted application for a complete understanding thereof.

e The pilot valve |05 is operated bythe electro- -magnet |01 which,fwhen=energized, causes Vopenlng of :the-pilot valve tofadmit compressed gas from the tank`99` to operate'the main 'inlet valve |113. Actuation ofthe main inlet 'valve vadmits vmove the linel of action of the spring 13 over- 'center to-thealeft offtlielinefIL-llf. The-spring; n aided by the spring W is their effectives to reversetlie movement ofithe l'atcl'iing1 mechanism andfreengage theflatching projection W with the roller 69'. During 'therelatchingmovementg the link 33 swings clockwise andi the link4 35i moves first' counterclockwise and' then clocllvvisel to its normal position. Duringthelatter part of this movement the latch surface of the-latchmember Z1i foilowsthe'roller 69 downwandi'y; the latchil;v rotating in a counterclockwise directionv about` its instant: center C' until 'the toggle- 41-53'1 is moved"I to*v its over'setv position by.v theA spring '59. The l breaker -is nowv latched'f in its closed.E position assliowni'n Fig. l. For illustrativepurposes; the invention y,is shownv applied toV a compressed? gasoperated closing mechanism for a circuit breaker: It will beobrvious, however, that the latch' mechanism is admirably adaptedl for use witlr othertypes operating mechanisms such, for instance; as a solenoidoperat'ed mechanism. It willbeapparentfrom theforegoing description that there is provided1v an inexpensive latch mechanism which permits high-speed openingof the breaker by quickly releasing the load and by permitting the holding latch surface to travel Va predetermined distance with the releasable mechanism. l Since there is no frictional load `on the latch, it may be made of ordinary steel instead of hardened steel heretofore used for latch mechanisms. Another advantage of the invention is that no special devices are needed to hold the latch open when the breaker is open.

Having described the invention in accordance with the patent statutes, it is to be understood that various changes and modifications may -be made in the structural details thereof without departing from some of the essential features-fof the invention. It is, therefore, desired that the languageof the appended claims be given as reasonably broad interpretation as the prior art permits. l

I claim as my invention:

1. In a circuit breaker provided with a biased member releasable to permit opening of thec'ircuit, in combination, a latch for engaging and restraining said releasable member in closed position, a plurality of movable support members for said latch, one of said support membersbeing collapsible to permit unlatching movement of said latch, said support members being disposed to permit a portion of said latch to travel with said releasable member during at least a portion of the unlatching movement.

2. In a cir-cuit breaker provided with a biased Y member releasable to effect opening of thecircuit, in combination, a latch member for engaging and restraining said member in closed position, a plurality of support members for pivotally supporting said latch at different points, means biasing said latch to latching position,` a toggle for restraining said latch in latchingi-pofornoating-movement in= latching and unlatchingfdirections, a toggle-for restraining said-latch in latching position, saidy toggle when actuated permitting the latch torelease saldi releasable member.

4; InA a circuit breakerl provided with al biased member releasable to. effect opening of the circuit; in combination, a. noatinglatch biased to latching position for engaging and restraining saidmemberin closed position1 a toggle biased to anA overset position for holdingy said: floating latchin latching position, and means for. actuating'saidftoggle l to cause theioating'latch to release said member, said' latch being supported in a manner to permit the latchv portion of the latch iso-travel with said member during apart o1' the unlatching movement;

5. Inl ai circuit breaker provided withI ay biased member-'releasable to permit opening of the cir-'- cuit, incombination, a latch for engagingl and restraining said releasable member in closed position, means biasing said latch to v latchingpositi'on, a tripping toggle for lrestraining said latch inlatching'y position, said toggle being operable to permit movement of said latch to unlatching position, -means supporting said latch to permit the latching portion thereof to travel with said releasable member during a part of the unlatching movement, and spring means biasing said tripping toggle to restraining position, said releasable member being effective in the open position to restrain said latch in unlatching posisition and operable to release the latch to thereby cause release of said releasable member,"s"a `id support members permitting the latch engaging portion of the latch to travel with the releasable member during a portion of the opening movement thereof.

3. In a circuit breaker provided with a releasable member biased to eiect opening of the circuit, in combination, a latch member biased to latching position for engaging and restraining said releasable member in closed position, a. plurality of support means for supporting said latch tion and to restrain said tripping toggle in nonrestraining position.'

6. In a circuit breaker provided with a biased member releasable to effect opening of the breaker, in combination, a floating latch for engaging and restraining said releasable member in closed position, an overcenter spring normally biasing said latch to latching position and operable during the unlatching movement to bias said latch in unlatching direction, means for releasably restraining said latch in latching position, said means being operable in response to abnormal circuit conditions to release said latch, and means supporting said latch to permit the latching surface thereof to travel with the releasable member during the first part of the unlatching movement said overcenter spring during the latter part of the latching movement acting to move said latch quickly to latching position.

7. In a circuit breaker, an operating rod movable with the breaker, a latch roller on said rod, a latch for engaging said roller to releasably restrain the breaker in closed position, a plurality of movable support members for said latch, means for restraining said latch in latching position, said means being operable to permit unlatching movement of said latch, and said support members being disposed to permit the latching surface of the latch to travel with said roller during a. portion of the unlatching movement.

8. In a circuit breaker having a biased member releasable to effect opening of the breaker, a latch for engaging and restraining said releasable member in closed position, an overcenter spring normally biasing said latch to latching position, restraining means for releasably restraining said latch in latching position, means for operating said restraining means to release said latch, means supporting said latch in a manner to permit the latching surface thereof to travel in the same direction as the releasable member during at least a portion of the unlatching movement of said latch, said overcenter spring acting during the latter part of the unlatchingV movement of said latch to bias the latch in unlatching direction.

9. In a circuit breaker comprising an operating memberbiased to cause opening of the breaker, a latch for engaging a part movable with said operating member t9 restrain said member in closed position, means for holding said `latch in latching position, said means being operable to permit movement of said latch to unlatching position, and an overcenter spring normally biasing said latch to latching position, said spring moving over center during movement of said latch to unlatching position to bias said latch in unlatching direction.

10. In a circuit breaker having a member releasable to eiect opening of the breaker, a floating latch for engaging and restraining said releasable member in closed position, an overeenter spring normally biasing said latch to latching position, a toggle for positively holding said latch in latching position, means for actuating said toggle to permit said latch to move to unlatching position to thereby release said releasable member, said overcenterf spring during` movement of said latch. to unlatching position moving over center tobias said latch in unlatching direction, a spring biasing said toggle to holding position and operable to start said latch in latching direction, said overcenter spring y during movement of said latch in latching direc, tion moving over center to actuate said latch to latching position. l1. In a circuit breaker'provided with abiased member releasable to effect opening of the circuit, a latch member supported on a pair of pivoted links having'their axes intersecting near the latch pointfor -releasably` restraining said biased member, and releasable means for controlling the movement of said latch on said pivoted links.

l2. In a circuit breaker provided with a member biased to effect opening of the breaker,v a floating latch. having no xed pivot, but having an instant pivot near the latch point for releasably restraining said biased member, and releasable means for controlling movement of; said floating latch about said instant pivot,

ROSWELLAC. VAN-SICKLE'. 

